In service station environments, fuel is delivered to fuel dispensers from underground storage tanks. The underground storage tanks are large containers located beneath the ground that contain fuel. A separate underground storage tank is provided for each fuel type, such as low octane gasoline, high octane gasoline, and diesel fuel. In order to deliver the fuel from the underground storage tanks to the fuel dispensers, a pump is provided that draws the fuel out of the underground storage tank and delivers the fuel through a main fuel piping conduit that runs beneath the ground in the service station. The pump may be a “submersible turbine pump.” An example of a submersible turbine pump can be found in U.S. Pat. No. 6,223,765 assigned to Marley Pump Company. Branch conduits from each fuel dispenser are coupled to the main fuel piping conduit so that fuel from the branch conduit can be delivered to the fuel dispenser.
Due to regulatory requirements governing service stations, the main conduit fuel piping is usually required to be double-walled piping. Double-walled piping contains an inner annular space that carries the fuel. An outer annular space surrounds the inner annular space so as to capture and contain any leaks that occur in the inner annular space. An example of double-walled fuel pipe can be found in U.S. Pat. No. 5,527,130, incorporated herein by reference in its entirety.
It is possible that the outer annular space of the double-walled fuel piping could fail thereby leaking fuel outside of the fuel piping if the inner annular space were to fail as well. Fuel sump sensors that detect leaks are located underneath the ground in the submersible turbine pump sump and the fuel dispenser sumps. These sensors detect any leaks that occur in the fuel piping at the location of the sensors. However, if a leak occurs in the double-walled fuel piping in between these sensors, it is possible that a leak in the double-walled fuel piping will go undetected since the leaked fuel will leak into the ground never reaching one of the fuel leak sensors. The submersible turbine pump will continue to operate as normal drawing fuel from the underground storage tank; however, the fuel may leak to the ground instead of being delivered to the fuel dispensers.
Therefore, there exists a need to be able to monitor the entire double-walled fuel piping system to determine if there is a leak in the double-walled fuel piping that could cause fuel to leak outside of the double-walled fuel piping.